Process of purifying crude synthetic camphor



, commercial purposes.

fotented I 53, L126,

7 tuft? col: 4

JOHAN-NES E'Z KESSLER, OF WEST CHARGE, NEVJ JERSEY. .dSSlC-INOR TO E. I. 33D POINT DE NEMGURS 613 COMPANY, OF VJILMING-TON, DELAKKKABE, A EORPORA'EION OF DE) AYVARE.

'ERQGESS OF IUEIFYING CRUDE SYNTHETIC CAEHFHQR.

No Drawing.

To e 5 'wlzo'm it may concern:

lie it known that l, JoHANNns M. K 5 ton, citizen of the United f'ltzrtes, and resident of West Orange, in the county of and Stateot New Jersey have invented av certain new and useful Process of Purifying Crude Synthetic Camphor, of which the following is it specification.

This invention relates to illQPllllfiCfLilOll of synthetic camphor contaminated with certain organic impurities, and comprises suhjocting said cemphor to :1 prolonged heat treatment preferably at a pressure substantially shove atmospheric pressure.

In the manufacture of synthetic csmphor from turpentine the formation of pincnc hydrohalide, such as pinene hydrol'rhloride, is usually one of the first operations to he carried out. Although it is relatively easy to convert this latter substance into camphene and from there into borneol and finally into camphor, small amounts of organic halides, such for example as colophene chloride, etc, are teneciously retained throughout the dirierent stages of the manufacture and their removal from the final product was found impossible in some cases or could only be accomplished with consid ershle difiiculty by expensive purification processes. Quite often the incl: of proper refining methods was the main reason Why synthetic. cs-mpl'lor contaminated with traces of organic chlorides, but otherwise showing the songs vslnniole properties as the natural product, could not be employed for most I The amount of organic chlorides present in the synthetic. osmphor may have been less than 1% and still such a, product was liuhle to gradually split off free hydrochloric acid and so cause.

serious trouble wherever employed. Pillticulerly serious and objectionahle was the behavior-of such synthetic cainphor when it occurred in nitrocellulose plastics such as celluloid, pyralin, etc, which consist of approximately nitrocellulose and 30% compiler. Discoloration of the more delicately colored compounds, instabi ity and Application filed Tannery 1?, 19526.

other (lamees by starting; discoloral for example at a temperature above 190 (3.,

Serial No. 351,936.

l'lir-ulty which is ordinarily en- L The chicr i countered in the refining of synthetic carnphor by dry disi'i lzilioiu is the development of tree hydrochloric acid and an oily, yellow 4. colored, acid reacting; liouid which condenses on the sides ot the chzunher into which the csimphor vapor i led and by (lro Pun g' into the run-in portion of the properly refined product contaminates it. presence of rec hydrochl uic acid is not only very ohjectionnlfl on account of its destructive ac tion on the metal lined calnphor suhliiniug chambers but is apt to cause very serious non nr stability, and consequent decompo. the nitrocellulose when the latter is made into plastics with caniphor containing it. i

Experiments were tried to refine the crude material by first steam distilling it from a 10% caustic soda, solution drying the distillete and submitting it finally to dry distillation. Although steam distillation removed most of the tarry impurities and yielded a neutral product greatly ini loved in color but not yet satisfactory, its c ilorino content was hardl diiierent from that of the original cernphor, indicating the presence of chlorides of considerable "tiibility. Dry distillation of the steam distilled and dried cnmphor yielded :r-product contzunincted with free hydrochloric acid to almost the some extent direct dry distillation of the crude. i

As the result of my researches, 1 dis covered that it completely satisfactory prod not, free from chlorine, could he obtained by first subjecting the dry crude synthetic cmnphor to it long continued halting process,

and under pressure; the eliect of this treatment is to break down any chlorides present into neutral, chlorinefree bodies and tree hydrochloric acid After, removal of the arid, the csmphor may be readily obtained to in condition lay distilling it under normal pressure-in the regular manner. Starting out with practically dry crude synthetic camphor with a chlorine contentoi to .070, heating it Well above its boiling point in a sealed glass tube or an iron autoclave and afterwards distilling gave the following results 3 hrs. halting at 230 (I. left chlorine in the distilled cainphor.

10 hrs. baking at 230 C. left 0. 6% chlorine in the distilled camphor.

20 hrs. baking at 230 C. left chlorine in the distilled camphor.

30 hrs. baking at 230% C. left no cholorine in the distilled camphor.

As an exan'iple of carrying out my invention, crude synthetic camphor is dried and melted at a temperature of about 175 C. in a steel retort or autoclave provided with a valve to permit and control the of steam. When all the water is driven oil the valve is closed and the heat increased to approximately 225 to 235 U; the pressure is maintained at from 25 to 30 pounds per square inch above atmospheric pressure. The hydrogen chloride resulting from decomposition of the organic chlorinecontaiir ing substances present in the crude synthetic camphor is allowed to escape from the retort occasionally. The heating at a temperature between about 225 and 235 C. is continued until tests indicate that no more acid is driven off; from 20 to 30 hours baking is usually required to complete the reaction. After decreasing the i'zem ierature in the rctort to about 210 C. and. reducing slowly the pressure in the retort by opening again the above mentioned valve for a few seconds, the camphor is then distilled and condensed in chambers in the usual manner.

Purified synthetic camphor can also be obtained from the properly baked crude product according to methods other than distillation. F or example, the baked synthetic camphor may be dissolved in an organic solvent such as ethyl alcohol, naphthe, etc., and crystallized from a. hot saturated solution on cooling or from an unsaturated solution on concentration by distillation. Any-dirt or insoluble material. present in such a solution can be removed by filtration through cloth or other filtering mediums.

Instead of baking the crude and dried synthetic camphor ata temperature of about 230 (1, it is possible to bring about decomp sition of the organic chlorides by baking at a temperature of, say, 205 (1,, and at, or slightly above, atmospheric pressure, for about 10 hours, distillin the camphor, subjecting it to another baking treatment at the same temperature (205-210 C.) for 5 or 6 hours, and

one

escape again subjecthig the calm.

phor to dry distillation. I prefer, however, the more simple procedure of baking for from 20 to 30 hours at a temperature betu'een225 and 235 0.

Although I have mentioned specifically the use ol temperatures 11 J to 235 C. and pressures of 25 to 30 pounds, these pressures being such as can be safely used in retorts oi. ordinary boiler steel plate construction, my invention includes carrying out the bale ing operation at higher temperatures and higher pressures up to the point at which the camphor itself begins to decompose.

I claim:

lf'lhe process which comprises heating crude synthetic camphor for from about 20 to 30 hours at a temperature above 190 C. and below that at Which camphor itself be gins to decompose. l 2. The process of separating organic chlorides from impure cainphor containing said chlorides which comprises heating said camphor at a temperature suilicient to decompose said organic chlorides but insullicient to decompose the camphor until decomposition of said chlorides is substantially completed.

3. The process of separating organic chlorides 't'rom impure camphor containing said chlorides which comprises heating said impure camphor substantially free from Water for from about 20 to 30 hours at a temperature of from about 225 to 235 C.

l. The process of separating organic chlorides from impure camphor containing said chlorides which comprises heating said impure camphor substantially free from Water for from about 20 to 30 hours at a temperature of from about 225 to 235 C. While permitting any hydrogen chloride which is formed to escape during the heating period.

5. The process of separating organic chlorides from impure camphor containing said chlorides which comprises heating said impure camphor substantially free from water for from about 20 to 30 hours at a temperature of from about 225 to 235 C. and at a pressure of from about '25 to 30 pounds above atmospheric ressure, While permitting any hydrogen 0 l'oride which is formed to escape at intervals during the heating period.

6. The process which comprises heating crude synthetic camphor substantially free 7. The process of purifying crude synfor from about 20 to' 30 hours i thetic eamphor containing organic chlorides Y which comprises baiting said crude camphor substantially free from. water at a temperatuie snllicient to decompose the organic chlorides into products coinprisin hydrochloric acid gas, but insnlficient to tecompose the caniphor itself. permitting the hydrochloric acid gas to escape at intervals during the baking,

8. The process of purifying crude synthetic cainplior containing organic chlorides which comprises halting; said crude cainplior substantially free from \ziltl' at a temperature of from about 225 to 235 C. and at a pressure of from about to 30 pounds above atmospheric pressure, permitting the hydrochloric acid gas to escape at intervals during the baking; and finally distilling the camphor under atmospheric pressure.

and finally distilling the campholz.

'9. The process which comprises heating thoroughly dried crude synthetic camphoi for from about 20 to 30 hours at a temperature above 190? C. and below that at which camphor itself begins to decompose.

10. The process of separating organic chlorides from impure camphor containing said chlorides which comprises heating s-iid impure camphor to drive oi? moisture contained therein and then further heating the resulting dried camphor for from about; 20 to 30 hours at a temperature of from about to 235 C.

In testimony whereof I aliix my signature.

JOHANNES M. KESSLER. 

